A technical paper by, M. Grenstein, P. Lum, H. Yoshida, M.S. Seyed-Bolorforosh, "A 2.5 MHz 2-D Array With Z-axis Backing", IEEE Ultrasound Symposium, San Antonio, Tex., Nov. 3, 1996, describes an array of high density piezoelectric elements that are useful in an ultrasound imaging transducer assembly, the piezoelectric elements generating a sequenced or phased array of ultrasonic pulsed signals in separate signal channels. The transducer assembly comprises a front of an ultrasound imaging probe assembly that is manipulated to probe a desired portion of the body of a medical patient. The transducer assembly generates pulsed ultrasonic signals that are reflected by the probed portion of the body, the reflected signals are transmitted to an electronic medical apparatus, which is an electronic apparatus that scans the signals to produce an electronically generated image of the portion of the medical patient that is being probed. The piezoelectric elements of the ultrasonic imaging probe assembly are individually connected via a backing material to individual, signal transmitting, circuits.
Various forms of backing material are described in, Kremkau, Frederick W., Diagnostic Ultrasound, W. B Saunders Co., Philadelphia, Pa. 1993. In a patented probe, described in U.S. Pat. No. 5,482,047, the piezoelectric elements of the ultrasound imaging probe assembly are individually connected, via circuitry, to individual wires of an electrical cable. The individual wires are coaxial cables that transmit the pulses and the reflected signals between the probe assembly portion of the probe and the electronic medical apparatus. According to U.S. Patent Application, Serial No., unknown, filed Oct. 29, 1997, and claiming the benefit of provisional application 60/032,769, Filed Dec. 11, 1996, piezoelectric elements of the ultrasound imaging probe assembly are individually connected by circuitry on a flexible printed circuit, and from there, to signal transmitting conductors of individual coaxial cables.
A main objective is to produce a large number of signals in an imaging transducer assembly of an ultrasound imaging probe assembly of limited size to increase the density of the signals, and, hence, to increase the resolution of the image.
In the past, coaxial shielding has been necessary to prevent unacceptable levels of cross talk among the signal transmitting conductors. Each of the signal transmitting conductors is concentrically encircled by a conducting shield, to comprise a coaxial cable. A major cost of manufacturing coaxial cables resides in the consumption of time and materials for applying the shield on each coaxial cable.